Gaah, you're making me choose?! Hrm...while I do like Galahad (-looks at name-) a lot, it's a tie between Herbert and Bedevere. Herbert because he's so adorable, with his random bursts of music and Bedevere because even though he's so poorly underwritten and neglected, I just have a soft spot for him.

Lancelot and Herbert, because I love the trend of random big gay musical numbers, and they're just funny. Then Sir Robin, Sir (Dennis) Galahad and the Lady of the Lake.
Hey, I think I'm the first one to acknowledge Dennis as a favorite.